The present application relates to preparing an alloy film in a sputter chamber. More specifically, the application relates to preparing the alloy film with a vertically variable and flexible alloy composition.
In many cases, a property of a material can be altered significantly by changing the properties of its surface. In other cases, providing a material composition gradient can provide improved functionality. Examples include the hardening of a metal surface by introducing a gradual composition change of metallic towards ceramic properties to improve mechanical properties, such as abrasion resistance, impact strength, etc., or buffer layers in between two distinct materials to improve adhesion or to provide specific electronic functionality as well as material gradients to provide anti-reflective properties in optical coating technology. Other examples include the formation of bandgap gradients in thin film alloy semiconductor films.
In current conventional practice, thin film manufacturing and semiconductor manufacturing techniques are limited. One such technique employs a sputter chamber to deposit a thin film on a substrate by sputtering a block of source material onto the substrate. Sputter deposition typically takes place in a vacuum using a sputter gas, such as Argon. Sputtered atoms ejected into the gas phase are not in their thermodynamic equilibrium state, and tend to deposit on all surfaces of the vacuum chamber. A substrate placed in the chamber will be coated with a thin film of the source material. Sputtering takes place with argon gas plasma, or another inert gas in a plasma state, as well as a target material, such as a semi conductive material, a metallic material, or a buffer material.